The present invention relates generally to a carton having a pair of panels secured together by locking means in a mutually overlapping relationship and, more particularly, to a carton having improved locking means that is hardly loosened or disengaged.
Wraparound paperboard cartons have been known as means for packaging in one unit a plurality of beverage cans or bottles. To form packages with wraparound cartons, the carton blanks are supplied to a packaging machine where each blank is applied to the exterior of a group of cans or bottles followed by interlocking of the opposite ends of the respective blank by a suitable means such as an adhesive. By this means, each blank is formed into a tubular carton.
As an alternative to adhesives, the so-called mechanical locks have been used to secure the opposite ends of carton blanks. An example of the mechanical lock may be found by reference to U.S. Pat. No. 4,077,095 which is hereby incorporated by reference. The mechanical lock disclosed in this patent is a locking means for securing together the first and second opposite end panels of a blank in an overlapping relationship. The locking means comprises a locking tab struck from the first panel, a retaining tab struck from the second panel and a locking aperture defined by the retaining tab in the second panel. The locking tab is foldably joined at its proximal end to the first panel whereas the retaining tab is foldably joined at its proximal end to the second panel. The blank is applied to a group of articles, and then the first and second panels are controlled to be in an overlapping relationship to form a composite bottom wall of the carton whereupon the locking tab is folded upward into the locking aperture. When the locking tab is moved into the aperture, the retaining tab is thrust aside by the locking tab and is thereby folded upward to define an angle with the second panel. This brings the retaining tab into abutment at its free end against the lower side of the locking tab, which in turn retains the locking tab in the folded position. In this manner, the locking tab is held in the locking aperture with the perimeter of the aperture in engagement with the locking tab.
Another example is illustrated in U.S. Pat. No. 4,093,116 owned by the applicant. There is disclosed a panel interlocking arrangement comprising a locking tab arranged to be driven through a locking aperture defined by a retaining tab. Holding means is formed in the locking tab for receiving the free end of the retaining tab to hold the locking tab and the retaining in angular based relation to each other. There further comprises a securing tab projecting from the transverse edge of the locking aperture which is disposed within a securing aperture disposed at the base of the locking tab to positively secure the panels together against relative movement.
Wraparound cartons are tightly wound around groups of articles with no slack to assure that the articles are held inside the cartons. Therefore, the locking means such as mentioned above continually undergoes tension. If a carton with the locking means is subjected to vibration during, for example, its transportation, the locking tab could be unfolded to some degree, which in the worst case could result in disengagement of the retaining tab from the underside of the locking tab. Once the tabs are disengaged, the carton could be loosened to the extent that the accommodated articles are dislodged from the carton.
What is needed, therefore, is a wraparound carton having an improved locking means wherein unfolding of the locking tabs are practically inhibited